UNBORN babies practice crying and smiling while still in the womb, a study has discovered.

Researchers from Durham University say fetuses try out facial expressions such as grimacing, furrowing their brows and wrinkling their nose long before they are born.

Importantly, rehearsing these mannerisms in the womb means babies can communicate pain or distress to their parents as soon as they are born.

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The joint study with Lancaster University, published today (June 5) in the academic journal PLOS One, studied 15 fetuses at two-week intervals between 24 and 36 weeks gestation.

Research leader Dr Nadja Reissland, senior lecturer in developmental psychology at Durham University, said they were able to identify 19 separate small movements which eventually combined to form single distinguishable expressions.

Movements appear to increase significantly during the gestation period, progressing from simple actions such as the widening of the lips, to more complex expressions whereby up to five movements come together to form a whole. Expressions include crying and smiling as well as pain-like mannerisms, identified by simultaneously furrowing the brow, wrinkling the nose and raising the lip.

The eight-year project applied a facial action coding system, used to study adult facial expressions, to the unborn and used advanced imaging to produce frame-by-frame pictures of fetuses in the womb.

Dr Reissland said: "At the moment there is no link between these expressions and emotions".

She said that expressions do not always reflect feelings and it remains undetermined if fetuses can feel pain, but she believes that these expressions are: "practiced by the fetus in the womb to get ready for life after they are born.

"It is vital for infants to be able to show pain as soon as they are born so that they can communicate any distress or pain they might feel to their carers and our results show that healthy fetuses ‘learn’ to combine the necessary facial movements before they are born.

"It is not yet clear whether fetuses can actually feel pain, nor do we know whether facial expressions relate to how they feel".

Dr Reissland suggests that a yawning movement made by the fetus stimulates the brain area to begin experimenting further with movement.

Evidence also suggests that there is no difference in the rate of facial development between male and female fetuses during this period.

Dr Reissland said the finding was: "a significant stepping stone in our understanding of fetal development".

Though the link between facial movements and emotions awaits further research, she added that: "facial movement could soon become related to the effects of the mother smoking or taking drugs.

This could eventually give doctors a new insight into the health of fetuses, and the development of inter-uterine procedures, which could be used to improve the health of an ailing fetus.